Combustion equipment



June 24, 1969 v err. HARDING 3,451,216

COMBUSTION EQUIPMENT Filed April 28. 1967 v Sheet of 2 INVENTOR Gordon Thomas Harding Misegades & Dougla ATTORNEYS Sheet I Filed April 28, 1967 FIG.4

United States Patent 3,451,216 COMBUSTION EQUIPMENT Gordon Thomas Harding, Whetstone, England, assignor to The English Electric Company Limited, London, England, a British company Filed A r. 28, 1967, Ser. No. 634,762 Claims priority, application Great Britain, Apr. 28, 1966, 18,655/ 66 Int. Cl. F02c 7/ 04; F230 7/00; F23m 9/00 US. Cl. 6039.65 1 Claim ABSTRACT OF THE DISCLOSURE Combustion equipment, e.g. for a gas turbine engine, having a flame tube of which the upstream end is closed and which has air inlet ports between the upstream and downstream ends of the flame tube, through which primary air is introduced in the direction towards the closed upstream end of the flame tube, the direction of flow at the periphery of the frame tube being towards the upstream end, and the direction of flow in the centre of the flame tube being towards the downstream end.

The primary air may also flow transversely over a face of the burner before the air takes part in combustion with the injected fuel, thereby keeping the burner face free of carbon.

This invention relates to combustion equipment. Such combustion equipment is used, for example, in gas turbine engines.

According to this invention in one aspect, combustion equipment includes a flame tube into which air is introduced between the ends of the flame tube, and means to direct the air towards a substantially closed end of the flame tube, the air first flowing adjacent to the flame tube wall, being then reversed, and flowing in the direction away from the substantially closed end in the region substantially midway between the flame tube walls.

According to this invention in another aspect combustion equipment includes a flame tube into which inlet air is introduced in such a manner that said inlet air flows transversely over a face of a burner before said inlet air takes part in combustion with fuel injected from the burner into said inlet air, said inlet air travelling initially in a generally upstream direction and being then reversed and flowing in the opposite direction in the region substantially midway between the flame tube Walls.

A number of embodiments of the invention will now be described with reference to the accompanying drawings, of which:

FIG. 1 is a longitudinal section through part of a combustion chamber of a gas turbine engine,

FIG. 2 is a view similar to FIG. 1 of a second embodiment,

FIG. 3 is a view similar to FIG. 1 of a third embodiment,

FIG. 4 is a view similar to FIG. 1 of a fourth embodiment, and

FIG. is a view similar to FIG. 1 of a fifth embodiment.

Referring to FIG. 1, the gas turbine engine has combustion equipment including an outer pressure-resistant casing 11 into which air is delivered from the compressor. Mounted within the casing 11 is a flame tube 12 which is closed by a wall 13 at its upstream end, and from the downstream end of which (not shown) combustion gases are delivered to a turbine to drive it. The upstream end of the flame tube 12 is formed of a tubular portion 14 of smaller diameter than the downstream portion 15 of the flame tube, the two portions being joined by a transice verse wall 16. Immediately on the upstream side of the transverse wall 16 there are provided two rows of swirl vanes, 17 and 18, each of which extends circumferentially round the upstream portion 14 of the flame tube. The rows of swirl vanes 17, 18, are secured between the transverse wall 16 and a flange 19, and each may take the form of separate rectangular plates having flanges at their axially spaced ends, or alternatively of continuous corrugated parts. The swirl vanes 17, 18 are inclined to the radial direction to give a circumferential component of velocity to the air entering between adjacent vanes. A further transverse member 20 is secured between swirl vanes 17 and swirl vanes 18, and projects into the interior of the upstream portion 14, carrying a short cylindrical member 21 at its inner end, concentrically within and spaced at a short distance from the wall of the upstream portion 14 of the flame tube.

On the upstream side of the swirl vanes 17 the portion 14 is provided with sockets 22 housing burners 23 through which fuel is supplied for combustion. The fuel is injected in an atomised spray in well-known fashion.

A further row of swirl vanes 24 connects the transverse wall 16 with the downstream portion 15 of the flame tube, the swirl vanes 24 being larger than those above-mentioned.

In operation, primary combustion air enters the flame tube through the row of swirl vanes 17 and is deflected by member 21 to flow along the inside of the wall of the upstream portion 14 towards the upstream end of the flame tube. It flows transversely over the faces of the burners 23 and is reversed in direction by the transverse wall 13 so as to flow in the downstream direction in the region substantially in the center of the flame tube. It then passes centrally through the member 21, and further air entering through swirl vanes 18 is deflected in a downstream direction and is added to the burning primary air. The swirl vanes 18 may cause the air to rotate in the same direction as that entering through swirl vanes 17, or in the opposite direction.

Continuous combustion is ensured by the recirculation of the burning gases, which is in the anticlockwise direction as seen in the top half of FIGURE 1.

Further air is added through swirl vanes 24 for the completion of combustion or for dilution of the burning gases, and if desired still further ports (not shown) may be provided further downstream in the flame tube wall.

Referring to FIGURE 2, instead of burners 23 positioned in apertures in the cylindrical wall of the upstream portion 14 of the flame tube, there is provided a burner 25 positioned in an aperture in the upstream end wall 13 on the center line of the flame tube.

Referring to FIGURE 3, instead of rows of swirl vanes 17, 18, and members 20, 21, there are provided swirl vanes 27, 28, which may be in the form of circumferentially-corrugated strips, disposed between cylindrical parts of the upstream portion 14 of the flame tube wall and the cylindrical member 31. These will have substantially the same effect on the air as swirl vanes 17, 18. Moreover, in FIGURE 3, in place of the swirl vanes 24 there is provided a row of swirl vanes 34, in the form of a circumferentially-corrugated strip between the downstream end of the upstream portion 14 of the flame tube and the upstream end of the downstream portion 15.

Referring to FIGURE 4, instead of the transverse member 20 being between two rows of swirl vanes 17, 18, it is secured on the downstream side of a single row of swirl vanes 17 and carries at its inner end a cylindrical member 32 which is somewhat longer than the corresponding member 21 of FIGURE 1. The downstream end of member 32 is outwardly flanged, and a row of swirl vanes 38 is secured between the outward flange and a transverse wall 33, which carries a cylindrical member 34 at its inner end. The cylindrical member 32 is spaced from the cylindrical wall of upstream portion 14, and the cylindrical member 34 is spaced from the downstream end of the cylindrical member 32 to cause air entering through swirl vanes 17, -38 to flow in the upstream direction immediately inside the respective walls. A further row of swirl vanes 24 is provided, the downstream end of cylindrical member 34 being spaced from the downstream portion 15 of the flame tube so as to direct the air entering through swirl vanes 24 in the downstream direction. The swirl vanes 24 are exactly the same as in FIGURE 1, except that they are arranged in a ring of substantially equal diameter to that of swirl vanes 17 rather than of larger diameter as in FIGURE 1.

Referring to FIGURE 5, there is shown yet another variation, in which swirl vanes 27, in the form of a circumferentially-corrugated strip, are secured within the downstream end of the upstream portion 14, and have a frusto-conical member 42 secured within them. The downstream end of this member is flanged and secured to swirl vanes 38 as described in relation to FIGURE 3.

Where one or a number of cylindrical flame tubes are used, the region midway between the flame tube walls will be adjacent the centre-line of the flame tube; where the flame tube has two annular walls, this region will be adjacent the centre-line of a section through that part of the flame tube on one side of the axis of symmetry of the annulus.

It will be understood that the generally upstream direction of flow is that to the left, and the generally downstream direction of flow is that to the right, in the drawings. Moreover, the flame tube 12 will normally be surrounded by an outer casing 11 in all constructions; and

4 the invention may be applied irrespective of whether each flame tube 12 has a surrounding casing 11; or Whether an annular assembly of individual tubular flame tubes 12 is contained in an annular casing 11; or whether both the flame tube 12 and the casing 11 are annular.

What is claimed is:

1. Combustion apparatus comprising a tube having an open downstream end and an end wall closing the upstream end; air inlet openings situated intermediate the ends of the tube; vanes for directing the air flow from the openings in an upstream direction towards the closed end wall, and with a circumferential swirl component; and a plurality of liquid fuel nozzles situated at circumferentially spaced points around the tube at an axial location intermediate the air inlet openings and the closed end Wall, for delivering substantially the whole combustion fuel supply in the form of fuel sprays substantially radially into the tube; the closed end wall being shaped for deflecting the upstream air flow inwards so as to return the air flow in a downstream direction along a generally axial stream lying within the initial upstream flow.

References Cited UNITED STATES PATENTS 2,907,171 10/1959 Lysholm 6039.65 2,930,192 3/1960 Johnson 6039.65 3,064,424 11/1962 Tomlinson 6039.65 3,306,333 2/1967 Mock 60-3965 XR JULIUS E. WEST, Primary Examiner.

US. Cl. X.R. 

